Image selection might be lost by accident without notice

[derselbst]

Suppose the user opens a single image and swipes through other images in that directory while selecting images. Move, hardlink or delete operations are only affecting the image currently displayed. Hence, if the user hits ESC for switching over to thumbnail view, the ImageSectionDataContainer with all the selected images will be destroyed and the selection is lost without notice.

Two problems must be addressed:

a) Notification of loss of selection must be done in DocumentView as well.
b) If somehow must be possible to apply a file operation to all the checked files from the DocumentView.

Possible solutions for b):

1. The ImageSectionDataContainer of the currently active DocumentView with all its images should initialize the model of the ThumbnailView.

Pro: loading times in large directories can be reduced.
Con: Sorting of that DataContainer will not match the previously saved sorting of the ThumbnailViewer model and must be either overriden or expensively re-sorted.

2. Change the DocumentView to apply FileOperations to all selected images

Pro: Easy to implement
Con: Unintuitive, there might be non-visible side-effects as the user doesn't see which images were selected.

3. Disable selecting images in DocumentView if DataSectionContainer mismatches the DataContainer of the Model.

Pro: Intuitive
Con: Hard to implement, considering changing directories, closing and reopening of the ThumbnailView window, etc.